Pyrometer structure



. Dec. '3, .1940. H. w. 'DlETERT PYROMETER STRUCTURE Fild June 19 1939 2 Sheets- -Sheet YFIGQS.

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I NV EN TOR.

T m R 0 H E A m Y R R A s Y B Dec; 3, 1940. 4 H. W.'D|ETERT 2,223,408

" PYROMETER STRUCTURE Filed.June' l9, 19:59 2 Sheets-Sheet 2 i I y INVENTOR.

v ARRY W. DIETERT ATTORNEYS Patented-Dec. 3, 1940 sf PATENT OFFICE PYROMETEB STRUCTURE Barry W. Dieter-t, Detroit, Mich. Application June 19, 1939, Serial No'. 279,962

7 Claims.

This invention relates generally to instruments for measuring the temperature of molten metal such as molten grey and white iron and refers more particularly to immersion instruments of this type having a thermocouple and a meter. Usually at predetermined intervals of' time, preferably every half hour, the thermocouple is inserted for a depth of three to six inches in the molten metal in a ladle from a cupola to W. obtain on the meter of the instrumentthe correct reading of the temperature of the "molten metal. Thus, a very valuable guide for controlling the operation 'of the cupola will be maintained. 1

However, in the past the hot gases from the n lten metal have attacked the thermocouple and have changed the composition of the thermocouple elements or wires so that the callbrations thereof have been affected or impaired. As a result, the reading was inaccurate.

Therefore, one of the essential objects of the present invention is to provide such instruments with efii cient means for protecting the thermocouple elements from the gases at elevated temperatures, for example, from 500 F. up so the thermocouple will retain its calibration for'lts entire life.

Another object is to provide an instrument 30 wherein the thermocouple is constructedin such a way that the molten iron and slag will not adhere excessively thereto.

Another object is to provide a compact, portable instrument that is light in' weight, easily handled, anad accurate in operation.

Other objects, advantages and novel details of construction of this invention will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

Figure 1 is a perspective view of apyrometer embodying my invention;

. Figure 2 is a side elevation, partly in section, of the construction shown in'Figure 1;,

Figure 31s a. fragmentary lan view of a portion of Figure 2;

Figure 4 is-a fragmentary plan view of another portion of Figure 2, with parts broken away for the sake of cleamess;

Figure 5 is an enlarged section taken substantially on the plane indicated by lines 5-.-5 of Fi ure 2;. v

Figure' 6' is'a section taken substantially on the line 8--6of Figure 5; c Figure 7 is'a longitudinal section similar to Figure 5, but showing'a modification of the invention! Figure 8 is the line 8- 8 of Figure '7.

co 7 Referringnow to the drawings. A is .theframe,

a section taken substantially on B is the thermocouple, and C' is device embodying my invention.

As shown, the frame A'comprises a pair of spaced junction boxes and 2, an intermediate tube 3 terminally connected to said boxes, and

the meter of a a handle 4 projecting rearwardly from the junction box 2.

The thermocouple B extends downwardly at a slight angle from the junction box at the outer end of the frame so as to be readily insertable into molten metal in a ladle (not shown) from a cupola,

Junction box 2 at the inner end of the frame so as to be readily readable by the operator.

Inthe present instance the thermocouple elements preferably comprise a'wire 5 of platinum and a wire 6 of similar metals havediflferent E. M. F. potentials at elevated temperatures and are received within a ceramic tube 1 having low thermo-expansion characteristics. As shown,. and 6 are secured together .at thelower end of the tube 1 to provide a junction 8, while the tube 1 is provided throughout its length with two laterally spaced longitudinally extending bores 9 and III for the. wires 5 and 8. Preferablythe lower end of the tube is sealed about said junction 8 to protect the wires from the hot gases" from the molten metal.

Receiving and protecting this tube 1 is-a tube ll. of carbon or of ceramic or carbon base materials such as graphite or graphite clay. The lower end of this tube II is also close c When assembled, the open upper end oi. the outer tube II is clamped in a. tubular part l2 of the junction box I, and the open upper end of the inner tube 1 extends upwardly above the openend of the outer tube II and is held in place by a collar l3 and set screws respectively, within the tubular part I2 of the junction box.' The wires 5 and 6 project upwardly from theopen'end of the tube and are connected to suitable terminals l6 and I1 in the Junction box. Extending compensating leads l8 and gitudinally of the tube Ito respectively, in the junction box 2. Preferably the terminal 20 constitutes one post for the meter, while the terminal 2| is connected by a suitable resistance coil 22 for the meter. As shown,

posts 20 and 23; respectively,

into molten metal in a ladle from a cupola,

while the meter 0 is mounted ontheplatinum'rhodium. These disthe wires '5' from the terminals l8 and II are l9 that extend-m. terminals and 2i,

to the other post 23- the meter is conventional in construction andhas a dial 2 and. a-

said dial. As usual. the

Thus, when the thermocouple Btis inserted.

the wires 5 and B produce an electromotive force (E. M. F.) proportional to the heat to which the junction 8 of the wires of the thermocouple is subjected. The movement of the pointer 25 over the dial 24 of the meter is proportional to the E. M. F. applied to it from the thermocouple via the compensating leads l8 and I9. Consequently, the movement of the pointer is proportional to the heat to which the thermocouple is subjected. In view of this, the dial 24 is calibrated in degrees Fahrenheit to indicate the temperature of the molten metal.

In the process of construction the wires 5 and 6 are first secured together at one end to provide the junction 8. The free ends of the wires are then inserted into and through the bores 9 and I in the tube 1 until the junction 8 is at one end of the tube. This end is then sealed by a ceramic mixture 3| for example, a mixture of silica and aluminum, which is preferably fused by an electric are or high temperature flame upon said end of the tube about the junction 8.

As an alternative, a hollow tube 40 of fused quartz or other ceramic material may be used as a housing for the wires and 6. trated in Figures '7 and 8, the lower end of this tube 40 is sealed, and the wires 5 and 6 are separated in the tube by two solid rods 4| and 42 of fused quartz. Preferably these rods 44 and '42 are arranged side by side and project approximately one-half inch above the upper end of the tube '40 so that they may be readily grasped and removed. As shown, the combined diameters of said rods are substantially equal to the inside diameter of the tube 40 whereby the rods are in engagement with opposite-sides of the tube while in engagement with each other.

Thus, from the foregoing it will be apparent that two important steps have been taken to protect the thermocouple elements 5 and 6 from the hot gases. First, the lower end of the tube 1 containing these. elements is sealed regardless of whether such tube has one or two bores, and, second, the tube containing these elements is provided with an outer protecting tube II which is constructed to withstand the action of the molten metal temperature. As a result of this combination a cheaper outer tube may be employed.

If desired, a shield such as D may be provided at the lower end of the tubular part l2 of the junction box I to keep the heat from the molten metal going up into the junction box I and tube 3. Preferably this shield D comprises a rela tively hard disk 50 of insulating material and is bolted to a metal flange 5| of the tubular part l2. A layer 52 of relatively soft insulating material is employed between the disk 50 and flange 5| to complete the assembly.

What I claim as my invention is:

1. In an instrument of the class described, a hollow tube of ceramic material having a sealed immersion end, a removable partition of ceramic material extending lengthwise of the interior of said tube and terminating short of the sealed immersion end thereof, said partition consisting of two solid rods arranged side by side, the combined diameters of said rods being substantially equal to the inside diameter of the tube whereby said rods are in engagement with said tube at diametrically opposite sides thereof while in engagement with each other and divide the tube lengthwise into two chambers, and thermal elements having different E. M. F. potentials extending lengthwise of the interior of said tube,

AS lllUS- one in each chamber, and provided between the sealed end of the tube and the adjacent end of the partition with a junction.

2. In an instrument of the class described, a hollow tube of ceramic material having a sealed immersion end, a removable partition of ceramic material extending lengthwise of the interior of said tube and terminating short of the sealed immersion end thereof, said partition consisting of two solid rods arranged sideby side, the combined diameters of said rods being substantially equal to the inside diameter of the tube whereby said rods are in engagement with said tube at diametrically opposite sides thereof While in engagement with each other and divide the tube lengthwise into two chambers, thermal elements having different E. M. F. potentials extending lengthwise of the interior of said tube, one in each chamber, and provided'between the sealed end of the tube and the adjacent end of the partition with a junction, and an outer protecting tube of carbon 'and ceramic material receiving the sealed immersion end of the tube aforesaid and having a sealed immersion end.

3. In an instrument of the class described, a thermocouple comprising a hollow tube having low thermo-expansion characteristics, said tube having a sealed immersion end, thermal elements having different E. M. F. potentials extending lengthwise of the interior of said tube and having a junction at the immersion end thereof, and means for insulating-said thermal elements from each other consisting of two solid rods of ceramic material extending lengthwise of the interior of said tube, said rods being arranged side by side between said-thermal elements and throughout their length being'in engagement with each other and in engagement with diametrically opposed "sides of said tube, said rods normally projecting beyond the other end of said tube so as to be accessible for removal purposes.

4. In an instrument of the class described, a thermocouple having a; hollow tube provided with a sealed immersion end, thermal elements having different E. M. F. potentials extending lengthwise of the interior of said tube and having a junction at the immersion end thereof, and means within said tube for separating the thermal elements from each other consisting of two rods of fused quartz arranged side by side within the tube between the thermal elements, said rods terminating short of the junction, the combined diameters of the rods being substantially equal to the inside diameter of the tube so that the rods engage opposite sides of the tube while in engagement with each other.

5. In an instrument of the class described, a thermocouple having a hollow tube provided with a sealed immersion end, thermal elements having different E. M. F. potentials extending lengthwise of the interior of said tube and having a junction at the immersion endthereof, and means within said tube for separating the thermal elements from each other consisting of two rods of fused quartz arranged side by side within the tube between the thermal elements, said rods terminating short of the junction and projecting outwardly from the tube so that they may be readily grasped and removed, the combined diameters of the rods being substantially equal to the inside diameter of the tube so that the rods engage opposite sides of the tube while in engagement with each other.

6. In an instrument of the class described, a

I thermocouple having a hollow tube provided with a sealed immersion end. thermal elements in said the inside diameter of said tube whereby said rods engage opposite sides of said tube while in engagement with each other.

7. In an instrument of the class described, a

' thermocouple comprising a hollow tube having low thermoexpansion characteristics, said tube having a sealed immersion end, thermal eletube.

ments having diflerent E. a. F. potentialsextending lengthwise 01- the interior or said tube and having a junction at'the immersion end thereof, 7 and means for insulating said thermal elements from each other consisting of elongated members of ceramic material extending lengthwise of the interior of said tube, said members being arranged side by side between said thermal elements and engaging diametrically opposed sides 01- said tube, said members being entirely-free of capable of being readily withdrawn from said HARRY, W. DIETERT.

.said tube, thermal elements andiunction and 

